[Qemu-devel] [PATCH v2 1/3] Revert "chardev: Make the name of memory device consistent"

[Markus Armbruster <armbru@redhat.com>]

This reverts commit 6a85e60cb994bd95d1537aafbff65816f3de4637.

Commit 51767e7 "qemu-char: Add new char backend CirMemCharDriver"
introduced a memory ring buffer character device driver named
"memory".  Commit 3949e59 "qemu-char: Saner naming of memchar stuff &
doc fixes" changed the driver name to "ringbuf", along with a whole
bunch of other names, with the following rationale:

    Naming is a mess.  The code calls the device driver
    CirMemCharDriver, the public API calls it "memory", "memchardev",
    or "memchar", and the special commands are named like
    "memchar-FOO".  "memory" is a particularly unfortunate choice,
    because there's another character device driver called
    MemoryDriver.  Moreover, the device's distinctive property is that
    it's a ring buffer, not that's in memory.

This is what we released in 1.4.0.

Unfortunately, the rename missed a critical instance of "memory": the
actual driver name.  Thus, the new device could be used only by an
entirely undocumented name.  The documented name did not work.
Bummer.

Commit 6a85e60 fixes this by changing the documentation to match the
code.  It also changes some, but not all related occurences of
"ringbuf" to "memory".  Left alone are identifiers in C code, HMP and
QMP commands.  The latter are external interface, so they can't be
changed.

The result is an inconsistent mess.  Moreover, "memory" is a rotten
name.  The device's distinctive property is that it's a ring buffer,
not that's in memory.  User's don't care whether it's in RAM, flash,
or carved into chocolate tablets by Oompa Loompas.

Revert the commit.  Next commit will fix just the bug.

Cc: qemu-stable@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 qapi-schema.json |  6 +++---
 qemu-char.c      | 16 ++++++++--------
 qemu-options.hx  |  6 +++---
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/qapi-schema.json b/qapi-schema.json
index f82d829..a56de74 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3362,7 +3362,7 @@
                                  '*rows'   : 'int' } }
 
 ##
-# @ChardevMemory:
+# @ChardevRingbuf:
 #
 # Configuration info for memory chardevs
 #
@@ -3370,7 +3370,7 @@
 #
 # Since: 1.5
 ##
-{ 'type': 'ChardevMemory', 'data': { '*size'  : 'int' } }
+{ 'type': 'ChardevRingbuf', 'data': { '*size'  : 'int' } }
 
 ##
 # @ChardevBackend:
@@ -3397,7 +3397,7 @@
                                        'spicevmc' : 'ChardevSpiceChannel',
                                        'spiceport' : 'ChardevSpicePort',
                                        'vc'     : 'ChardevVC',
-                                       'memory' : 'ChardevMemory' } }
+                                       'memory' : 'ChardevRingbuf' } }
 
 ##
 # @ChardevReturn:
diff --git a/qemu-char.c b/qemu-char.c
index c86ce4b..bd1aefb 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2783,8 +2783,8 @@ static void ringbuf_chr_close(struct CharDriverState *chr)
     chr->opaque = NULL;
 }
 
-static CharDriverState *qemu_chr_open_memory(ChardevMemory *opts,
-                                             Error **errp)
+static CharDriverState *qemu_chr_open_ringbuf(ChardevRingbuf *opts,
+                                              Error **errp)
 {
     CharDriverState *chr;
     RingBufCharDriver *d;
@@ -2796,7 +2796,7 @@ static CharDriverState *qemu_chr_open_memory(ChardevMemory *opts,
 
     /* The size must be power of 2 */
     if (d->size & (d->size - 1)) {
-        error_setg(errp, "size of memory chardev must be power of two");
+        error_setg(errp, "size of ringbuf chardev must be power of two");
         goto fail;
     }
 
@@ -3105,12 +3105,12 @@ static void qemu_chr_parse_pipe(QemuOpts *opts, ChardevBackend *backend,
     backend->pipe->device = g_strdup(device);
 }
 
-static void qemu_chr_parse_memory(QemuOpts *opts, ChardevBackend *backend,
-                                  Error **errp)
+static void qemu_chr_parse_ringbuf(QemuOpts *opts, ChardevBackend *backend,
+                                   Error **errp)
 {
     int val;
 
-    backend->memory = g_new0(ChardevMemory, 1);
+    backend->memory = g_new0(ChardevRingbuf, 1);
 
     val = qemu_opt_get_size(opts, "size", 0);
     if (val != 0) {
@@ -3724,7 +3724,7 @@ ChardevReturn *qmp_chardev_add(const char *id, ChardevBackend *backend,
         chr = vc_init(backend->vc);
         break;
     case CHARDEV_BACKEND_KIND_MEMORY:
-        chr = qemu_chr_open_memory(backend->memory, errp);
+        chr = qemu_chr_open_ringbuf(backend->memory, errp);
         break;
     default:
         error_setg(errp, "unknown chardev backend (%d)", backend->kind);
@@ -3775,7 +3775,7 @@ static void register_types(void)
     register_char_driver("socket", qemu_chr_open_socket);
     register_char_driver("udp", qemu_chr_open_udp);
     register_char_driver_qapi("memory", CHARDEV_BACKEND_KIND_MEMORY,
-                              qemu_chr_parse_memory);
+                              qemu_chr_parse_ringbuf);
     register_char_driver_qapi("file", CHARDEV_BACKEND_KIND_FILE,
                               qemu_chr_parse_file_out);
     register_char_driver_qapi("stdio", CHARDEV_BACKEND_KIND_STDIO,
diff --git a/qemu-options.hx b/qemu-options.hx
index 2dbfd42..7e30a81 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1782,7 +1782,7 @@ DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
     "-chardev msmouse,id=id[,mux=on|off]\n"
     "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
     "         [,mux=on|off]\n"
-    "-chardev memory,id=id[,size=size]\n"
+    "-chardev ringbuf,id=id[,size=size]\n"
     "-chardev file,id=id,path=path[,mux=on|off]\n"
     "-chardev pipe,id=id,path=path[,mux=on|off]\n"
 #ifdef _WIN32
@@ -1820,7 +1820,7 @@ Backend is one of:
 @option{udp},
 @option{msmouse},
 @option{vc},
-@option{memory},
+@option{ringbuf},
 @option{file},
 @option{pipe},
 @option{console},
@@ -1929,7 +1929,7 @@ the console, in pixels.
 @option{cols} and @option{rows} specify that the console be sized to fit a text
 console with the given dimensions.
 
-@item -chardev memory ,id=@var{id} [,size=@var{size}]
+@item -chardev ringbuf ,id=@var{id} [,size=@var{size}]
 
 Create a ring buffer with fixed size @option{size}.
 @var{size} must be a power of two, and defaults to @code{64K}).
-- 
1.7.11.7